Final answer:
The net ionic equation for the neutralization of added sulfuric acid by a buffer containing ammonia and ammonium chloride is NH3(aq) + H3O+(aq) → NH4+(aq) + H2O(l), demonstrating how the ammonia acts as a weak base to keep the pH stable.
Step-by-step explanation:
When a buffer containing significant amounts of ammonia (NH3) and ammonium chloride (NH4Cl) neutralizes added acid, specifically sulfuric acid (H2SO4), the ammonia present in the buffer reacts with the hydronium ions (H3O+) produced by the acid. This reaction serves to reduce the acidity of the solution by forming ammonium ions (NH4+), and is represented by the net ionic equation:
NH3(aq) + H3O+(aq) → NH4+(aq) + H2O(l)
This reaction essentially captures the core action that occurs in the buffered solution when acid is added: the weak base (NH3) reacts with the strong acid (H2SO4) component in the form of hydronium ions, mitigating a large pH change by forming its conjugate acid (NH4+).